This 1964 Chrysler Imperial LeBaron I found
for sale online probably does not share very many design characteristics
with the "M" Body other than the LeBaron part of the nameplate,
which would appear alongside the Diplomat thirteen years later.
The Imperial name would be assigned to the "M" body-derived
"J" body coupe from 1981 to 1983.

A 1970 Imperial LeBaron I found for sale.

Here's a 1975 Imperial LeBaron, one of the
last great battlecruisers of the road.